Laser in situ keratomileusis for myopia up to -11 diopters with up to -5 diopters of astigmatism with the summit autonomous LADARVision excimer laser system.

OBJECTIVE: To assess the safety and effectiveness of the Summit Autonomous LADARVision active tracking narrow beam excimer laser system for laser in situ keratomileusis (LASIK) correction of myopia and astigmatism. DESIGN: A multicenter, prospective noncomparative case series. PARTICIPANTS: This cohort consisted of 177 eyes corrected for spherical myopia up to -11 diopters (D) and 170 eyes corrected for myopia up to -11 D spherical equivalent with astigmatism up to -5 D. INTERVENTION: Treatments were performed at four sites in the United States using a 6-mm optic zone for spherical myopes and a 5.5-mm optic zone with a 1-mm blend for astigmats. MAIN OUTCOME MEASURES: Visual acuity, subjective refraction, vector analysis, subject satisfaction, intraocular pressure, complications, and adverse reactions. RESULTS: Six-month follow-up was available on 157 spherical eyes and 113 astigmatic eyes. For spherical myopes, uncorrected visual acuity (UCVA) was 20/20 or better in 60.5%, 20/25 or better in 80.3%, and 20/40 or better in 93.9%. The mean spherical equivalent was -0.29 +/- 0.45 D with 75.2% +/- 0.50 D and 94.9% +/- 1.00 D of intended. A loss of two lines of best spectacle-corrected visual acuity (BSCVA) occurred in 0.6%, and no eyes lost greater than two lines of BSCVA. For astigmatic myopes, UCVA was 20/20 or better in 52.0%, 20/25 or better in 74.5%, and 20/40 or better in 94.1%. The mean spherical equivalent was -0.23 +/- 0.49 D with 75.2% +/- 0.50 D and 95.6% +/- 1.00 D of intended. A loss of two lines of BSCVA occurred in 0.9%, and no eyes lost greater than two lines of BSCVA. Vector analysis showed that 99% of the intended cylinder was corrected on average with a mean angle of error of 4.2 degrees. Refractive stability was achieved between 1 and 3 months in 97.5% of spherical eyes and 99.4% of astigmatic eyes and confirmed between 3 and 6 months in 100% of both spherical and astigmatic eyes. CONCLUSIONS: Eyes treated for myopia up to -11 D of spherical equivalent with or without astigmatism up to -5 D show early refractive stability, good UCVA outcomes, no significant loss of BSCVA, accurate correction of astigmatism, and slight undercorrection without a change from the photorefractive keratectomy algorithm and with a single treatment.

Photorefractive keratectomy for low-to-moderate myopia and astigmatism with a small-beam, tracker-directed excimer laser.

OBJECTIVE: To assess the safety and effectiveness of the Autonomous Technologies Corporation LADARVision excimer laser system for photorefractive keratectomy correction of myopia and astigmatism. DESIGN: A multicenter, prospective, noncomparative case series. PARTICIPANTS: The cohort consisted of 467 eyes corrected for spherical myopia and 211 eyes corrected for myopia with astigmatism. INTERVENTION: Treatments were performed at six sites in the United States using a 6-mm ablation zone for spherical myopes and a 5.5-mm zone with a 1.0-mm blend for astigmats. MAIN OUTCOME MEASURES: Visual acuity, subjective refraction, corneal haze, intraocular pressure, complications, adverse reactions, patient satisfaction, and corneal endothelial changes. RESULTS: Twelve-month follow-up was available on 414 spherical eyes and 175 astigmatic eyes. The results for spherical eyes with correction between -1 and -5.99 diopters (D) were: uncorrected visual acuity (UCVA) of 20/40 or better achieved by 98.1%, 20/20 or better by 72%, 1.8% lost 2 lines and 0.3% lost greater than 2 lines of best spectacle-corrected visual acuity (BSCVA); 76.4% were within 0.50 D of the target correction and 94.4% were within 1.00 D. The results for myopia with astigmatism with spherical equivalent correction between -1 and -5.99 D were: UCVA of 20/40 or better in 97.4%, 20/20 or better in 61.7%, 2.5% lost 2 lines and no eyes lost greater than 2 lines BSCVA; 73.9% were within 0.50 D of the target correction and 95% were within 1.00 D. For spherical myopes combined with myopic astigmats corrected for 6 to 10 D, results were: UCVA of 20/40 or better in 93.4%, 20/20 or better in 61.2%, 2.3% lost 2 lines and no eyes lost greater than 2 lines of BSCVA; 67.2% were within 0.50 D of the desired correction and 87.8% were within 1.00 D. Refractive stability was achieved between 3 and 6 months for the spherical and astigmatic groups. No eyes had corneal haze graded as moderate or greater, and there was no significant decrease in endothelial cell density. CONCLUSIONS: Patients treated for 1 to 10 D of spherical equivalent myopia, with or without astigmatism, showed early refractive stability, excellent UCVA, no significant loss of BSCVA, no loss of endothelial cell density, and very low levels of corneal haze to 12 months after surgery.

Clear lens extraction with intraocular lens implantation for hyperopia.

PURPOSE: Current surgical options for the correction of moderate to severe hyperopia include hyperopic laser in situ keratomileusis (LASIK), phakic intraocular lens implantation and clear lens extraction with intraocular lens (IOL) implantation. We investigate the safety and efficacy of clear lens extraction with IOL implantation to correct hyperopia. METHODS: Phacoemulsification and IOL implantation was performed on 18 eyes of 10 patients. In 16 eyes, the Hoffer-Q formula was used for IOL power calculation and a single IOL was inserted; in the remaining 2 nanophthalmic eyes, the Holladay-II formula was used and two piggy-back IOLs were inserted. RESULTS: Mean preoperative spherical equivalent for distance was +6.17 D (range, +4.25 to +9.62 D). Patients were followed postoperatively for a mean of 10.5 months (range, 4 to 27 mo). Uncorrected visual acuity in all eyes was 20/50 or better with a median uncorrected visual acuity of 20/40 (range, 20/30 to 20/50). Two patients lost 2 lines of spectacle-corrected visual acuity; both of these patients achieved spectacle-corrected visual acuity of 20/30. CONCLUSIONS: Clear lens extraction with IOL implantation is a safe and effective procedure for the correction of moderate to severe hyperopia in the presbyopic age range.

Refractive keratotomy after photorefractive keratectomy.

BACKGROUND: The current surgical procedures available for the treatment of residual myopia and/or astigmatism after photorefractive keratectomy (PRK) include refractive keratotomy, laser in situ keratomileusis (LASIK), repeat PRK, or photorefractive astigmatic keratectomy (PARK). In this study, we investigate the safety and efficacy of refractive keratotomy for the correction of residual myopia and/or astigmatism after PRK. METHODS: Ten eyes of 9 patients underwent refractive keratotomy after excimer laser photorefractive keratectomy using the Lindstrom nomogram. PRK procedures were performed using the VISX 20/20 system by one surgeon. RESULTS: All eyes except one obtained an uncorrected visual acuity of 20/40 or better. One eye developed significant haze following PRK with myopic astigmatic regression and underwent refractive keratotomy to correct the residual refractive error. This patient was also the only patient who lost 2 lines of spectacle-corrected visual acuity secondary to corneal haze. CONCLUSION: This study demonstrates that refractive keratotomy can reduce residual astigmatism and myopia that may be present following excimer laser photorefractive keratectomy. Our results suggest there is no need to change the refractive keratotomy nomograms for eyes that have previously undergone PRK.

Bilateral photorefractive keratectomy with intentional unilateral undercorrection in an aircraft pilot.

An aircraft pilot had bilateral photorefractive keratectomy (PRK) with intentional undercorrection in the nondominant eye for best uncorrected far and near visual acuity (monovision). After PRK, the patient was able to pilot an aircraft with no deleterious effects directly related to surgery. Evaluation of similar cases and further study will allow consensus on whether PRK is appropriate in these patients.

Retrospective comparison of photorefractive keratectomy and radial keratotomy.

BACKGROUND: The efficacy and predictability of photorefractive keratectomy and radial keratotomy become increasingly relevant. This retrospective study compares one surgeon's experience with photorefractive keratectomy and radial keratotomy over a 3-year period from 1990 to 1993. METHODS: Photorefractive keratectomy was performed on 103 eyes of 76 patients that met the inclusion criteria for the phase IIb, phase III, and phototherapeutic keratectomy studies as delineated by the United States Food and Drug Administration. Radial keratotomy was performed on 117 eyes of 81 patients with up to 9.00 diopters (D) of myopia. RESULTS: In the photorefractive keratectomy group, 83% of the eyes achieved uncorrected visual acuity of at least 20/40; 37% saw 20/20; 88% had a refraction within 1.00 D of emmetropia, and 63% within 0.50 D of emmetropia. For the radial keratotomy group, 85% of the eyes achieved an uncorrected visual acuity of 20/40 or better; 27% saw 20/20; 88% had a refraction within 1.00 D of emmetropia; and 55% within 0.50 D of emmetropia. There were no serious complications, and only one single eye in each of the photorefractive keratectomy and radial keratotomy groups lost two lines or more of spectacle-corrected visual acuity. CONCLUSION: Photorefractive keratectomy and radial keratotomy are both effective procedures, and result in similar refractive outcomes for myopia of -1.00 to -9.00 D.

Excimer laser photorefractive keratectomy after radial keratotomy.

BACKGROUND: Correction of residual myopia after radial keratotomy may be attempted with repeated keratotomy surgery, but predictability can be less than satisfactory. Excimer laser photorefractive keratectomy (PRK) provides an alternative approach to improving the refractive result in these patients. METHODS: Twenty-five eyes of 20 patients at five clinical locations underwent PRK for residual myopia after radial keratotomy. The number of incisions ranged from 4 to more than 16. Clear zones ranged from 3 mm to 4 mm. Best corrected visual acuity was 20/20 or better in 16 of the 25 eyes, with a range from 20/12 to 20/80. Uncorrected visual acuity was 20/200 or worse in 15 of the 25 eyes, with a range from 20/25 to finger counting. The interval between radial keratotomy and PRK averaged 33.5 months, with a range from 5 to 96 months. Nineteen eyes had 6 months or more of follow up; 15 had 12 months or more. RESULTS: Corneal haze was maximal 1 month after surgery (mean +/- SE, 0.65 +/- 0.09), and declined to 0.35 +/- 0.16 at 12 months. Twelve months after PRK, mean keratometric readings were 40.19 +/- 0.81 diopters (D) and mean spherical equivalent refraction was -1.42 +/- 0.47 D. Nine (60%) of the 15 eyes with 12 months follow up were within 1 D of emmetropia and 12 (80%) were within 2 D. Eight (53%) of the 15 eyes had uncorrected visual acuities of 20/40 or better. Spectacle-corrected visual acuity in the eyes with 12 months follow up improved in 4, did not change in 4, and worsened in 6. CONCLUSIONS: The results of PRK are less predictable in eyes that have previously undergone radial keratotomy, and these eyes respond with more haze after PRK than normal eyes.

Treatment of corneal abrasions with soft contact lenses and topical diclofenac.

BACKGROUND: Treatment of corneal abrasions often involves antibiotic ointment and pressure patching. The corneal abrasions following excimer laser photorefractive keratectomy have been managed with disposable soft contact lenses and diclofenac (Voltaren) eye drops. METHODS: We report 13 patients with corneal abrasions from trauma or recurrent corneal erosions treated with application of a disposable soft contact lens and instillation of diclofenac and antibiotic eye drops. RESULTS: All 13 patients reported significant pain relief and all abrasions healed within 3 days (most within 24 hours). Two of the recurrent erosion patients suffered subsequent spontaneous abrasions and one of the traumatic abrasion patients developed a possible infectious keratitis which cleared without visual loss. CONCLUSIONS: In this small series, the combination of a disposable soft contact lens and the instillation of diclofenac drops provided significant pain relief while the abrasion healed and allowed the patients to function with binocular vision. This treatment regimen offers an alternative to pressure patching in the treatment of corneal abrasions.

Results of excimer laser photorefractive keratectomy for the correction of myopia.

PURPOSE: This report summarizes the authors' 3-year experience with excimer laser photorefractive keratectomy on 240 eyes of 161 patients. METHODS: With constant laser emission parameters, nitrogen flow across the cornea was used on 79 eyes, whereas 161 eyes had no nitrogen flow. Of the 240 eyes, 74 were operated on without suction ring fixation. Postoperative pain management included patching and oral analgesics in 77 eyes and the use of topical diclofenac or ketorolac and a therapeutic soft contact lens in 163 eyes. Follow-up ranged from 1 month (206 eyes) to 36 months (10 eyes). RESULTS: At 3 months, 88% (144 eyes) had uncorrected visual acuity of 20/40 or better; 86% (151 eyes) had corrected visual acuity to within +/- 1 diopter of intended correction, and 10% (17 eyes) lost two or more lines of best-corrected visual acuity. At 12 months, 89% (122 eyes) achieved uncorrected visual acuity of 20/40 or better, 79% (115 eyes) had corrected visual acuity to within +/- 1 diopter of intended correction, and 4% (6 eyes) lost two or more lines of best-corrected visual acuity. At 24 months, 92% (44 of 48 eyes) had uncorrected visual acuity of 20/40 or better, 86% (44 of 51 eyes) had corrected visual acuity to within +/- 1 diopter of intended correction, and 5% (2 eyes) lost two or more lines of best-corrected visual acuity. At 36 months, 90% (9 eyes) achieved an uncorrected visual acuity of 20/40 or better, 90% (9 eyes) had corrected visual acuity to within +/- 1 diopter of intended correction, and no eyes lost two or more lines of best-corrected visual acuity. CONCLUSIONS: The results obtained with one procedure are within accepted standards of accuracy for refractive surgery, and there is the potential for refinement of the final optical correction. Complication rates are low and are not vision threatening. They included increased intraocular pressure, epithelial "map dot" changes, and recurrent corneal erosion syndrome, "central islands," and others. Photorefractive keratectomy appears to be a safe procedure over the short and medium term.

Effect of nitrogen flow on recovery of vision after excimer laser photorefractive keratectomy without nitrogen flow.

BACKGROUND: Excimer laser (VISX) photorefractive keratectomy was performed using nitrogen flowing through the ocular fixation ring. It was felt that eliminating nitrogen flow may provide faster early visual rehabilitation. METHODS: Two groups of 50 consecutive eyes underwent photorefractive keratectomy with (N2 flow) and without (no N2 flow) nitrogen flow, and were evaluated at 1 month postoperatively. RESULTS: There were more under- or overcorrections exceeding 1.00 diopter (D) in the N2 flow than in the no N2 flow groups. Eighteen eyes in the N2 flow and 11 in no N2 flow groups saw 20/50 or less, without correction. Fourteen eyes in the N2 flow and nine eyes in the no N2 flow groups lost two or more lines of best spectacle-corrected visual acuity. Four eyes in the N2 flow and none in the no N2 flow groups increased more than 1.00 D of astigmatism. CONCLUSION: The elimination of nitrogen flow in photorefractive keratectomy performed with the VISX laser appears to improve visual results in the early postoperative period.

Traumatic corneal abrasions following photorefractive keratectomy.

BACKGROUND: During excimer laser photorefractive keratectomy, central Bowman's layer and superficial stroma are removed. A potential disadvantage of this technique is whether proper epithelization of the cornea will occur in the event of a corneal abrasion. A potential advantage of photorefractive keratectomy over radial keratotomy in the event of blunt trauma is the presumably sound structural integrity of the cornea following superficial removal of stroma in photorefractive keratectomy compared to the weakened cornea following deep incisions in radial keratotomy. METHODS: We report two patients who sustained corneal abrasions from blunt trauma to the eye and orbit following photorefractive keratectomy--one following a fist injury and the other following a karate kick. RESULTS: In both patients, the corneal abrasions healed without incident and without recurrent erosions and both corneas remained intact. CONCLUSIONS: Corneal abrasion following trauma in two patients who has undergone photorefractive keratectomy healed as expected in a normal cornea. Although it is uncertain whether the trauma in these patients would have been sufficient to rupture radial keratotomy incisions, as would be expected from a superficial photorefractive keratectomy, the corneas remained intact following blunt trauma.

A two-year experience with excimer laser photorefractive keratectomy for myopia.

PURPOSE: This report summarizes the authors' 2-year experience with excimer laser photorefractive keratectomy (PRK) on 160 eyes of 128 patients. METHODS: All eyes were treated with an excimer laser: fluence, 160 mJ/cm2; frequency, 5 Hz; ablation zone diameter, 5.0 to 5.5 mm; and depth per pulse, 0.21 to 0.27 microns. A suction fixation ring was used in all eyes either with nitrogen flow (79 eyes) or without nitrogen flow (81 eyes) across the cornea. Follow-up ranged from 1 month (152 eyes) to 24 months (12 eyes). RESULTS: At 3 months, 82% (139) of eyes achieved an uncorrected visual acuity of 20/40 or better; 83% were corrected to within +/- 1 diopter (D) of intended correction and 30% lost one line of best-corrected visual acuity. At 6 months, 88% (124) of eyes achieved an uncorrected visual acuity of 20/40 or better; 84% were corrected to within +/- 1 D of intended correction and 15% lost one line of best-corrected visual acuity. At 12 months, 91% (71) of eyes achieved an uncorrected visual acuity of 20/40 or better; 84% were corrected to within +/- 1 D of intended correction and 17% lost one line of best-corrected visual acuity. At 24 months, 100% (12) of eyes achieved an uncorrected visual acuity of 20/40 or better; 91.6% were within +/- 1 D of intended correction and 0% lost one line of best-corrected visual acuity. CONCLUSIONS: In eyes with a follow-up of 6 to 24 months, 77% to 100% achieved an uncorrected visual acuity of 20/40 or better and 84% to 92% were corrected to within +/- 1 D of the intended correction. The authors conclude that excimer laser PRK appears to be a safe procedure capable of correcting the eyes of patients with low to moderate myopia with approximately the same degree of accuracy as radial keratotomy.

One-year results of excimer laser photorefractive keratectomy for myopia.

BACKGROUND: Excimer laser photorefractive keratectomy for the correction of myopia is presently under investigation in the United States by the Food and Drug Administration (FDA). The Phase II-B FDA study is being conducted on 75 normally sighted myopic eyes utilizing three currently available excimer lasers. This report presents the 1-year results on 12 myopic eyes treated with the VISX excimer laser system at the Ellis Eye Center at Cedars-Sinai Medical Center in Los Angeles under the Phase II-B FDA protocol. METHODS: Twelve eyes of 12 patients with myopia between -1.75 and -5.00 diopters underwent 193 nm argon/fluoride excimer laser photorefractive keratectomy. The epithelium was mechanically removed, and fixation was accomplished with a suction ring which provided nitrogen flow across the corneal surface. The computer controlled corneal ablations were 5.00 mm in diameter and were accomplished with an iris diaphragm closing from large to small. RESULTS: The preoperative spherical equivalent myopia was -3.50 D (SD = 1.02) and the postoperative myopia was -0.25 (SD = 0.48). Eleven of the 12 patients achieved an uncorrected visual acuity of 20/30 or better and were corrected to within +/- 0.50 D of emmetropia. All corneas demonstrated a mild reticular subepithelial haze which was barely visible at 1 year. There were no vision-threatening complications and none of the eyes experienced a loss of best corrected visual acuity. CONCLUSIONS: In this small trial, the excimer laser appears to be capable of accurately changing the refractive power of the cornea for the correction of myopia with minimal side effects. Only when larger numbers of patients undergo the procedure will we be able to determine the safety and efficacy of photorefractive keratectomy as a refractive surgical procedure.

Excimer laser myopic photorefractive keratectomy after undercorrected radial keratotomy.

Two patients, a 41-year-old female diabetic and a 37-year-old male, were undercorrected after radial keratotomy (spherical equivalents of -3.25 diopters in each eye). Because they were unable to wear a contact lens and had uncorrected visual acuities of 20/400 and 20/100, respectively, they elected to undergo excimer laser photorefractive keratectomy to reduce the myopia by 3.00 D and 2.75 D, respectively. Three months postoperatively, both patients were within 0.50 D of emmetropia. Videokeratography demonstrated a fairly uniform zone of central flattening. The previous radial keratotomy surgery and the diabetes (in one patient) did not appear to complicate the surgery. Excimer laser photorefractive keratectomy appears to hold promise as a means of correcting eyes left undercorrected by radial keratotomy.

Ten years experience with a conservative approach to radial keratotomy.

This retrospective study reports the results of radial keratotomy surgery on 225 eyes of 135 patients by one surgeon. Fifty-one percent of the eyes had four incisions and 45% had eight as the initial procedure. Fifteen percent of the eyes repeated surgery. The mean preoperative spherical equivalent refraction was -5.10 diopters (SD 1.90, range 1.20 to 11.60 D) and at 3 months to 1 year, the mean was -0.60 D (SD 1.00, range -4.80 to +3.40 D). For the entire series, 69% of the eyes achieved an uncorrected visual acuity of 20/40 or better, 73% were corrected to within +/- 1.00 D of emmetropia, and 3% were overcorrected by more than +1.00 D. For eyes with low preoperative myopia (-3.00 D and less), 100% achieved an uncorrected visual acuity of 20/40 or better, 97% were corrected to within +/- 1.00 D of emmetropia, and 3% were overcorrected by more than +1.00 D. For eyes with moderate myopia (-3.1 to -5.9 D), 73% achieved an uncorrected visual acuity of 20/40 or better, 81% were corrected to within +/- 1.00 D of emmetropia, and 3% were overcorrected by more than +1.00 D. For eyes with higher preoperative myopia (-6.0 to -11.60 D), 47% achieved an uncorrected visual acuity of 20/40 or better, 45% were corrected to within +/- 1.00 D of emmetropia and 3% were overcorrected by more than +1.00 D. One hundred eyes with a follow-up of 2 years or greater were studied for stability; 77% changed by less than 1.00 D from the 1 year value; 17% changed by 1.00 D or more in the hyperopic direction; 6% changed by 1.00 D or more in the myopic direction. There were no vision threatening complications and only one eye had a postoperative best spectacle corrected visual acuity of less than 20/40.

Effect of thermokeratoplasty on corneal curvature.

A cadaver eye model was used to evaluate and quantify the use of thermokeratoplasty for steepening the central cornea to correct hyperopia. Four groups of eye-bank eyes were treated with four separate surgical plans. Each plan involved the placement of controlled thermal burns (in the depths of the corneal stroma, using a cautery probe) applied in a radial pattern up to a premarked optical zone. The plans differed in the sequence of surgical steps. All plans progressively added radials and applications (to decrease optical zone) in various sequences. Corneal curvature was measured at baseline and at each surgical step. As more surgery was done within each plan, the corneas became progressively steeper. Total mean changes in corneal curvature ranged from 16.26 diopters to 19.76 diopters, depending on the plan. At each optical zone, as the number of radials increased, the effect increased. With progressively smaller optical zone size, the effect also increased.

Clinicopathologic study of healing excimer laser radial excisions.

Four radial linear excisions were created by an argon fluoride (193 nm) excimer laser in the edematous cornea of a blind eye of a diabetic human patient. Partial thickness corneal trephinations were performed at 3, 7, and 18 months after surgery for histopathologic examination. At 3 months, a wide gap in Bowman's layer permitted extension of an epithelial plug to a depth of 0.35 mm; at 7 and 18 months, the depth of the epithelial plug was decreased to 0.29 mm and 0.01 mm, respectively. With wound healing, excision width decreased and the two cut ends of Bowman's layer were almost reapposed by 18 months, suggesting wound contraction. Linear excisions with the excimer laser appear to be wider than incisions made with a diamond blade, but the pattern of wound maturation appears to be similar.

A simple, convenient tonometer tip disinfection technique.

A simple tonometer tip disinfection system is described. 10% sodium hypochlorite (household bleach) in a contact lens vial is taped to the base of the Goldmann applanation tonometer. The tonometer tip is then soaked for ten minutes in this vial.